Problem 36 - A Complete Resource Book in Chemistry for JEE Main

Question

Ozone is an important constituent of stratosphere because it (a) removes poisonous gases of the atmosphere by reacting with them (b) destroys bacteria which are harmful to human life (c) prevents the formation of smog over large cities (d) absorbs ultraviolet radiation which is harmful to human life

Step-by-Step Solution

Answer

(d) absorbs ultraviolet radiation which is harmful to human life

Step 1: Understanding the Role of Ozone

First, consider the primary role that ozone plays in the stratosphere. Ozone is known for its ability to absorb ultraviolet (UV) radiation.

Step 2: Analyzing Each Option

Let's evaluate the options: - (a) Removing poisonous gases: While ozone can react with certain pollutants, its primary role in the stratosphere isn't detoxifying gases. - (b) Destroying bacteria: Ozone can kill bacteria, but this occurs more in water purification processes, not in the stratosphere. - (c) Preventing smog: Smog formation is more related to lower atmospheric chemical reactions involving ground-level ozone rather than stratospheric ozone. - (d) Absorbing ultraviolet radiation: The primary role of stratospheric ozone is absorbing UV radiation, protecting life forms on Earth from harmful effects.

Step 3: Identifying the Correct Option

Based on the analysis, option (d) "absorbs ultraviolet radiation which is harmful to human life" is the correct statement describing the importance of ozone in the stratosphere.

Key Concepts

Stratospheric Ozone

In the atmosphere, ozone exists primarily within a layer known as the stratosphere. This stratospheric ozone is crucial as it serves as Earth's protective shield. Composed of three oxygen atoms, ozone's fundamental role is to filter out harmful portions of solar radiation. Despite its small concentration, stratospheric ozone absorbs a significant portion of the sun's ultraviolet (UV) rays. Without it, life on Earth would face severe threats.

• Stratospheric ozone is different from ground-level ozone, which can be a pollutant.
• Ozone formation and destruction are parts of a natural cycle, sensitive to human interference.
• It is commonly referred to as "the ozone layer," although it isn't an impenetrable barrier but a dense part of the upper atmosphere.

Understanding the nature of stratospheric ozone helps underscore its critical value in maintaining life on the planet.

Ultraviolet Radiation Absorption

One of the ozone layer's most vital functions is absorbing ultraviolet radiation, notably UV-B and UV-C types. As sunlight reaches Earth, different wavelengths of UV are filtered out at varying altitudes. The higher energy, shorter wavelength UV-C is mostly absorbed by oxygen, while UV-B, which can cause skin cancer and cataracts, is absorbed by ozone in the stratosphere.

• UV-A rays, with longer wavelengths, reach the Earth's surface in larger amounts but are less energetic.
• UV-B and UV-C can cause more harm because of their higher energy nature.
• Ozone depletion, characterized by reduced absorption capability, could lead to increased UV exposure.

This process of UV absorption not only protects humans but also sustains environmental equilibrium, keeping ecosystems balanced by regulating the amount of UV near the Earth's surface.

Atmospheric Protection

Ozone's function in atmospheric protection is critical, acting as Earth's sunscreen. This protection is vital not only to human health but also to plant life, marine ecosystems, and materials that degrade faster under intense UV exposure.

• Stratospheric ozone is instrumental in mitigating the effects of global warming by maintaining the temperature balance of the Earth.
• Ozone fluctuations can affect weather patterns, polar ice melting, and ocean currents due to temperature changes.
• This atmospheric barrier is essential for reducing the risk of skin cancers and protecting the immune systems of humans and wildlife.

Protecting the stratospheric ozone layer is intertwined with safeguarding life and maintaining environmental stability.

JEE Main Chemistry

In the context of competitive exams like JEE Main Chemistry, understanding the role of ozone and its chemical properties can be crucial.

• Questions may revolve around the chemical reactions involving ozone, its formation, and decomposition.
• Students should grasp concepts such as ozone's interaction with UV light and its subsequent protective role.
• An understanding of environmental implications, such as ozone layer depletion and its causes, might also appear in exam questions.

This knowledge base is not only essential for exams but also for developing an understanding of broader environmental chemistry, emphasizing how chemical principles apply to real-world scenarios like atmospheric protection.